The present invention concerns displays used for electronic instruments and other devices and pertains particularly to rapid graphical analysis of waveforms using a pointing device.
A spectrum analyzer displays the amplitude of signals on the vertical (y) axis and frequency on the horizontal (x) axis. For some existing spectrum analyzers, when observing a measured signal, the displayed frequency component can be adjusted using start, stop, center or span controls. This is typically accomplished using a knob, step keys or direct numerical input. Generally, varying any of these parameters requires several steps and is not immediately intuitive. For example, to zoom in on a specific signal typically requires alternating between the center and span controls.
For further information on how center, start, stop and span controls work on existing spectrum analyzers, see for example, the User's Guide Agilent Technologies ESA Series Spectrum Analyzers, available from Agilent Technologies as Manufacturing Part Number E4401-90236, December 2001, pages 111–113.